BGP without MPLS?

Designing and operating large BGP networks has always been a challenge, as you have to deploy BGP on all core routers and design a hierarchy of internal BGP routers to get around the full-mesh limitation. When MPLS was introduced, it gave us means of deploying BGP only on the network edges, with the core routers carrying just the information about the BGP next hops.

As I know some of you run large networks, could you help me understand what you're using (without giving away too much information, of course):

  • Are you running a BGP network without MPLS or are you using BGP on the edges and MPLS transport in the core?
  • If you have a large number of BGP routers, do you have a nice hierarchy of BGP route reflectors (or confederations) or ad-hoc implementation where every router has all neighbors as RR-clients?

Full disclosure: I might use the information you give me in an upcoming article.

5 comments:

  1. In the big ISPs I've been working at, it was full mesh in the core (with confed for one and without for the other one), and then RR to the CPE.
    Never removed BGP in the core for Internet backbones.

    Nice blog by the way. :)

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  2. Completely BGP-free core network. MPLS and RSVP (for 3-play) only. BGP only on edges, RRs also there.
    have a nice article :)

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  3. BGP core. BB routers full mesh and acting as RR to edge routers. L2TPv3 is used to implement MPLS services (no LDP needed:) ) at the edge. Separate RR for VRFs.

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  4. Reasonably large european ISP.

    BGP Free Core.
    OSPF, LDP and PIM in Core.
    BGP on edges.
    Separate RRs for ipv4 and vpnv4.
    Redundant RRs

    ReplyDelete
  5. nice article.... From my experience and above comments, it looks like BGP in core wins :)...

    ReplyDelete

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Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.